Abstract:

Densities, areal biomass, and median shell length were determined monthly for the marsh snails Littoraria irrorata, Melampus bidentatus, and Neritina usnea at the same three marsh sites near Louisiana Universities Marine Consortium’s (LUMCON) DeFelice Marine Center in Cocodrie, Louisiana that were sampled in Hill and Roberts, 2017 [GRIIDC datasets R1.x139.143:0053 (DOI: 10.7266/N72V2D1T), R1.x139.143:0054 (DOI: 10.7266/N7Z31WKW), R4.x264.000:0006 (DOI: 10.7266/N7TM7858), and R4.x264.000:0007 (DOI: 10.7266/N7K35RQ4)]. Sampling occurred between January 2017 and December 2019 and included collecting all snails present in three 0.25 m x 0.25 m quadrats. The snails were sorted by species, shell lengths were determined for each individual snail, and the areal ash-free dry mass (AFDM) was determined by species per plot.

Suggested Citation:

Roberts, B.J.. 2020. Marsh snail densities, biomass, and lengths at LUMCON area salt marshes, 2017-2019. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-6x71-ja10

Purpose:

This work provides a unique temporal dataset for an abundant marsh invertebrate at multiple marsh sites that can be related to plant, soil, and water characteristics.

Data Parameters and Units:

Year: year of sampling; Month-name: month of sampling (3 letter month abbreviation); Month-number: month of sampling (1= Jan, 2 = Feb, etc.); Site: site identifier for each marsh location; Latitude: latitude of the marsh site in decimal degrees; Longitude: longitude of the marsh site in decimal degrees; Plot: identifier that refers to the specific sampling quadrat (out of 3 total) at each site; Littoraria irrorata density (snails/m2): number of individual snails of L. irrorata per square meter present in the plot; Melampus bidentatus density (snails/m2)” number of individual snails of M. bidentatus per square meter present in the plot: Neritina usnea density (snails/m2): number of individual snails of N. usnea per square meter present in the plot; Total snail density (snails/m2): number of individual snails of all species combined per square meter present in the plot; Littoraria irrorata biomass (g/m2): ash-free dry mass (AFDM) (g/m2) of all L. irrorata snails per square meter present in the plot; Melampus bidentatus biomass (g/m2): ash-free dry mass (AFDM) (g/m2) of all M. bidentatus per square meter present in the plot; Neritina usnea biomass (g/m2): ash-free dry mass (AFDM) (g/m2) of all N. usnea per square meter present in the plot; Total snail biomass (g/m2): ash-free dry mass (AFDM) (g/m2) of all snails of all species combined per square meter present in the plot; Littoraria irrorata shell length (mm): median shell length (mm) of all L. irrorata snails present in the plot; Melampus bidentatus shell length (mm): median shell length (mm) of all M. bidentatus present in the plot; Neritina usnea shell length (mm): median shell length (mm) of all N. usnea present in the plot.

Methods:

The sampling methods employed in this dataset are based on those detailed in Hill and Roberts (2017) and Rietl et al. (2018). Briefly, three 0.25m x 0.25m quadrats were randomly placed within a region ~20m from the marsh site at each of three marsh sites. Within each quadrat, all snails are collected. In the lab, the snails were sorted by species, the length of each individual snail measured and the areal biomass of each species quantified by determining the total ash-free dry biomass (AFDM) of all snails of that species in the plot.

Provenance and Historical References:

Hill, T. D., & Roberts, B. J. (2017). Effects of seasonality and environmental gradients on Spartina alterniflora allometry and primary production. Ecology and Evolution 7(22): 9676–9688. doi:10.1002/ece3.3494 Rietl, A. J., Sorrentino, M. G., & Roberts, B. J. (2018). Spatial distribution and morphological responses to predation in the salt marsh periwinkle. Ecosphere, 9(6), e02316. doi:10.1002/ecs2.2316

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